Posted by Darin Fisher, VP Engineering, Chrome The last sessions of the Chrome Dev Summit 2015 are coming to a close, so it’s the perfect time to reflect on the event. We started our annual summit back in 2012, where we first introduced Chrome on Android. Today, there are more than 800 million monthly active users on Chrome for Android.

The greatest power of the Web is in its reach—not just across devices and operating systems, but in reaching users. Top mobile web properties are seeing 2.5 times the number of monthly unique visitors compared to the top mobile apps, and mobile web reach is growing at more than twice the rate of mobile app reach. This reach offers a unique opportunity to engage with more users. We believe this is a pivotal moment for the web platform, as early adopters of a set of key enabling technologies and tools are seeing success. During the keynote, we covered the evolution of the mobile platform and the shift towards “progressive web apps,” which are fast, robust, app-like experiences built using modern web capabilities. The web has come a long way, and building immersive apps with web technology on mobile no longer requires giving up properties of the web you’ve come to love. Flipkart’s new mobile web experience is a great example of a progressive web app that uses the new capabilities to provide a next-generation user experience.

In practice, progressive web apps have three main aspects that separate them from traditional websites: reliability, performance, and engagement.Reliability

Every web app should load quickly, regardless of whether a user is connected to fast Wi-Fi, a 2G cell network, or no connection at all. We envision service workersas the ideal way for developers to build web apps that are resilient despite changing and unreliable networks. We've released twolibrariesto help take the work out of writing your own service worker:sw-precacheandsw-toolboxfor your App Shell and dynamic content, respectively. Once your implementation is up and running, you can easily test it on different network connections using Chrome DevToolsandWebPageTest. Service workers are already seeing great adoption by developers: there are currently 2.2 billion page loads a day using service workers, not counting its use in the New Tab page in Chrome.Performance

The RAIL performance model helps you figure out what a user expects from each interaction with your site or app, breaking down performance into four key goals:

Responses (tap to response) should be less than 100ms

Animations (scrolling, gestures, and transitions) should run at 60 frames per second

Idle time should be used to opportunistically schedule non-essential work in 50ms chunks

Traditionally, users have had a hard time re-engaging with sites on the web.Push notificationsenable you to build experiences that users can engage with "outside of the tab"--they don’t need to have the browser open, or even be actively using your web app, in order to engage with your experience. Best of all, these notifications appear just like other app notifications. Currently we’re seeing over 350 million push notifications sent every day in Chrome, and it’s growing quickly. Beyond the Rack has foundthat users arriving to their site by push notifications browse 72% longer than average users and spend 26% more.Tools for Success

Finally, Google is committed to making web developers successful. As our generalized library for building components on the web,Polymer is also deeply focused on helping developers achieve RAIL. Since its 1.0 release at Google I/O earlier this year, it has grown to be used on over 1 million web pages, including more than 300 projects within Google. Polymer 1.0 was 3 to 4 times faster than the previous 0.5 version, and the latest 1.2 release is even 20% faster than that. To get started with this modern way of thinking about web development, take a quick tour of Polymer, watch the Polymer Summit talks, check out the Polymer codelabs, or try thePolymer Starter Kit.We already have great resources likeWeb Fundamentalsthat we continue to expand and improve. We’re also committed to documenting each new feature we ship on the Mozilla Developer Network. In the past year alone, we’ve made 2,800 individual edits to MDN and created 212 new pages. To further our commitment to educating web developers, we’ve partnered with Udacity to offer a senior web nanodegree, an education credential focused on modern web technologies and techniques like service workers, Promises, HTTP/2 and more. For all the details on Chrome Dev Summit 2015, you can watchfull session videos, which we will continue to upload as they’re ready. Thanks for coming, thanks for watching, and most of all, thank you for developing for the web!